The Effect of Interface Geometry in Mixing of Two Co-Axial Supersonic Jets using Computational Fluid Dynamics

SCRAMJET is the only air-breathing engine that can achieve hypersonic speeds, accompanied by supersonic combustion. Because of its hypersonic speeds, the residence time of flow in combustor is in the order of milliseconds, which leads to improper mixing and continuous combustion. Thus, combustion has to be associated with holding a flame at high speeds, which makes stable and sustained combustion. To improve the flow mixing and flame holding mechanism in scramjet combustion, the mixing of co-axial jets needs to be analysed and the respective modifications should be made to achieve efficient combustion. The designing and meshing of geometry is carried out using structural meshing software ICEM CFD, before solving the flow in ANSYS Fluent. The analysis is carried for different equivalence ratio of fuel air mixture at various Mach numbers with reacting and non-reacting flows. Mach contours of non-reacting flow predict formation of shock waves and starting characteristics. Mass fraction contours of reacting flow give efficiency of combustion and mixing strength of combustor. CFD model is validated with results of Dual Combustion Ramjet engine.